Watching a Biography channel piece on Letterman he said that he wanted to get into late night talk because he watched Carson and 'he made it look SO easy that I figured I could do it.' The reality Letterman found when he started his late night show and his CBS show was that the job was anything but easy. Carson pulled it off with an style that looked effortless and COOL.
Even though Carson was probably way off the cutting edge in guests, humor or show style from 1975 on he still had enough Cool in his style to pull it off.
Cool can also be way over done. Being too cool for the room is a common phrase and for a reason.
Swing too hard and you will miss the ball a lot of the time. The same swing principle applies to your Cool on the air and in the produce. One of the 'coolest' icons in movies was probably James Dean in the 50s, but look at his movies - often his lines for a 2 hour flick would have fit on 1 page. It was his look, his eyes, his silence, and a careful pause in the timing that built his coolness.
How are you handling your cool factor? Is it in that delicate balance or is it overcooked or coming up rare?